VN3-12E indoor medium-voltage AC vacuum circuit breaker is a newest product designed by our company which is applicable to 3-phases AC50Hz, 12kV indoor switch systems. The product is with characteristics of smaller volume, reliable insulation, no pollution, long time free maintenance and so on. It is produced with standardized circuit breaker assembly line and has good performance and perfect quality. 1. Equipped with modularized operating mechanism which make the maintenance and the replacing are more convenient. The replace of module do not affect the dynamic capability and also shorten the power-off duration. 2. The interrupter and primary circuit are sealed in the epoxy resin, which makes the circuit breaker is more reliable 3. The pole using convected and ventilated technique and lower resistance vacuum circuit breaker limit the temperature rising because of circuit breaker working for a long time and also reduce the power loss. 4. The operating mechanism is designed uniquely and avoids the moving contact over-rebounding when the circuit breaker is opened and prolong the vacuum interrupter mechanical life. 5. Past the type test according to the national standards such as GB, DL, international standards of IEC, CEI, DIN, VDE and other major industrialized countries.